Core Muscles of the Trunk & Spine
The core muscles of the lower back and abdomen provide support for the spine. Core muscle
strengthening is very popular these days for treating and preventing back pain as well as
improved sports performance. Select the muscles below to view more details.
Rectus abdominus
The '6-pack' muscle at the front of the stomach
more
Internal obliques
Lateral abs which side-bend and twist the trunk
more
External obliques
Lateral abs which side-bend and twist the trunk
more
Erector spinae
Small muscles either side of the spine
more
Quadratus lumborum
Muscle between the pelvis and ribs which sidebends
more
Splenius
Split into two muscles, Splenis Capitus and Cervicis
more
Transverse abdominus
Also known as TVA, the deep core muscle
more
Multifidus
A series of small muscles on either side of the spine
more
The Main Core Muscles
The largest muscle of the trunk and spine is the errector spinae muscle which extends all the
way up the back of the spine. Other large muscles involved in moving and supporting the spine
are the large abdominal muscles, internal and external oblique muscles and the quadratus
lumborum muscles.
A number of smaller muscles are also involved which attach to the spine.

Rectus Abdominis



Rectus Abdominis is the most superficial of the abdominal muscles. It is this
muscle which forms the six-pack shape!
Origin

Crest of the pubis.

Pubic symphesis.
Insertion

Xiphoid process (base of the sternum).

5th,6th and 7th costal cartilages.
Actions

Flexes lumbar spine.
Innervation

Ventral rami of thoracic nerves.
Daily uses

Moving from lying to sitting.
Example strengthening exercises

Crunches or sit-ups.
Example stretches

Abdominal stretch.
Related injuries

Abdominal strain.
Related muscles

Internal obliques.

External obliques.
External Obliques



The obliques wrap around the trunk on each side to form our waists and join to
the linea alba, a band of connective tissue running down the front of the
abdomen. They help us to side bend and rotate the body.
Origin

Lowest 8 ribs.
Insertion

Front 1/2 of the iliac crest.

Linea alba.
Actions

Contraction of one side alone laterally bends the trunk to that side and rotates the trunk to
the other side.

Compresses the abdomen and supports the abdominal viscera.
Innervation

Ventral rami of thoracic nerves.
Daily uses

Raking leaves.
Example exercises

Twisting crunches.
Related injuries

Abdominal strain.
Related muscles

Internal obliques.

Rectus abdominus.
Quadratus Lumborum



The quadratus lumborum or QL is a common cause of back pain which is to one
side and comes on after lifting or twisting.
Origin

Posterior iliac crest.

Iliolumbar ligament.
Insertion

Twelfth rib.

Transerve processes of L1-L4.
Actions

Lateral flexion (side-bends) of the trunk.
Innervation

Ventral rami of the subcostal nerve.

Lumbar nerves.
Daily uses

Bending sideways to pick something up.
Example strengthening exercises

Side bends.
Related injuries

Hyperlordosis.
Related muscles

Internal obliques.

External obliques.
Transversus Abdominis



Transversus Abdominis is often abbreviated to TVA. This is a very important core
muscle which is vital in maintaining good posture. Activities such as Pilates focus
on contraction of the TVA.
Origin

Front of the iliac crest.

Inguinal ligament.

Costal cartilages of the lower 6 ribs.

Thoracolumbar fascia.
Insertion

Linea alba.
Actions

Compresses the abdomen and supports the abdominal visera.
Innervation

Ventral rami of thoracic nerves.

Ilioinguinal nerve.

Iliohypgastric nerve.
Daily uses

Maintaining good posture.
Example exercises

Core contraction exercises.
Related injuries

Lower back pain.
Related muscles

Rectus abdominis.
Internal Obliques



The internal obliques wrap around the waist and insert into the linea alba, a cord
like strip of connective tissue running down the centre of the abdomen. They help
to side bend and twist the body
Origin

Iliac crest.

Inguinal ligament.

Thoracolumbar fascia.
Insertion

Lower 3-4 ribs.

Linea alba.
Actions

Contraction of one side alone laterally bends the trunk to that side and rotates the trunk to
the other side.

Compresses the abdomen and supports the abdominal viscera.
Innervation

Ventral rami of thoracic nerves.

Ilioinguinal nerve.

Iliohypgastric nerve.
Daily uses

Raking leaves.
Example strengthening exercises

Twisting crunches.
Related injuries

Abdominal strain.
Related muscles

External obliques.

Rectus abdominus.
Erector Spinae
The erector spinae (sometimes known as sacrospinalis) is often described as a
group of different muscles called iliocostalis, longissimus and spinalis. Erector
spinae consists of lots of small fibres which are situated very close to the spine.
Origin

Posterior crest of the ilium.

Lower posterior surface of the sacrum.

Lower 7 ribs.

Spinous processes of T9-L5.

ransverse processes of T1-12.
Insertion

Angles of the ribs.

Transverse processes of all vertebrae.

Base of the skull.
Actions

Extension of the spine.

Lateral flexion (side-bending) of the spine.

Maintains correct curvature of the spine.
Innervation

Dorsal rami of cervical, thoracic and lumbar spinal nerves.
Example strengthening exercises

Dorsal raises.
Example stretches

Back arch stretch.
Related injuries

Lower back pain.
Related muscles

Multifidus.
Multifidus



Multifidus is a series of small muscles which travel up the length of the spine. It is
an important muscle in the rehabilitation of Gilmore's Groin and lower back pain.
Origin

Posterior surface of the sacrum.

Articular processes of the lumbar vertebrae.

Transverse processes of the thoracic vertebrae.

Articular processes of C3-7.
Insertion

Each part of the muscle inserts into the spinous process 2-4 vertebrae higher than its
origin.
Actions

Extension.

Lateral flexion.

Rotation of the spine.
Innervation

Dorsal rami of the spinal nerves.
Daily uses

Maintaining good posture of the spine.
Example strengthening exercises

Dorsal raises.
Example stretching exercises

Back arch stretch.
Related injuries

Lower back pain.
Related muscles

Erector spinae.